Tool holder, rotation tool, and combination of tool holder and tool

ABSTRACT

A tool holder has a base element, a deformable receiver for clamping a tool and at least one locking element configured for preventing an axial extraction of the tool from the tool holder through engaging a corresponding opposite element at the tool. The at least one locking element is integrally configured in one piece with the receiver.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of patent application Ser. No.13/728,094, filed Dec. 27, 2012, which was a continuation-in-part ofapplication Ser. No. 12/296,892, filed Oct. 10, 2008, now U.S. Pat. No.8,505,893 B2, which was a § 371 national stage filing of internationalapplication No. PCT/EP2007/003118, filed Apr. 5, 2007, which designatedthe United States; this application also claims the priority, under 35U.S.C. § 119, of German patent applications 20 2011 109 498.0, filedDec. 27, 2011, and 10 2012 110 392.5, filed Oct. 30, 2012; the priorapplications are herewith incorporated by reference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to tool holders comprising a tool holdingfixture, in particular shrink fit chucks and other chucks for receivingrotation tools, as well as to rotation tools for such tool holders.

Tool holders with clamping chucks, in particular shrink fit chucks, arewell known. They are being used for clamping tubular tools, turningtools, milling tools, reaming tools, and grinding tools, and similarthrough a thermally induced shrink process. Typically, such shrink fitchucks are thermally heated by an inductive shrink system, whereby theinner diameter of the shrink fit chuck is expanded. When the innerdiameter is enlarged, a tool to be clamped is inserted into the shrinkfit chuck, wherein the ratio of the inner diameter of the shrink fitchuck to the shaft diameter of the tool is configured, so that the toolis clamped torque proof in the shrink fit chuck after subsequent coolingof the shrink fit chuck.

From WO 01/89758 A1 it is known to inductively heat the sleeve sectionby means of an annular coil assembly, substantially surrounding thesleeve section in a coaxial manner. The coil assembly is connected to ahigh frequency AC generator and induces Eddy currents in the metalsleeve section, which heat the sleeve section. In order to avoid scatterflux and to concentrate the magnetic flux, magnetic flux concentrationelements made of soft magnetic electrically substantially nonconductivematerial, like e.g. ferrite or similar, are disposed at the faces and atthe outer circumference of the coil assembly, which direct the magneticflux generated by the coil assembly to the sleeve section of the toolholder, and in particular into the portion of the free end of the sleevesection.

The problem with tool holders comprising clamping chucks for rotatingtools which comprise cylindrical receiving shafts is the axial migrationof the rotation tool along the rotation axis of the clamping chuck outof the clamping chuck during operation. Said axial migration of therotating tool is caused by vibrations, which occur while machining thework piece with the rotating tool. Due to this detrimental effect, thework pieces cannot be machined precisely and according to theirdimensional specifications. Furthermore, canting the rotating tool inthe work piece or even in the clamping chuck receiving the work piececan lead to dangerous accidents. Under non-favorable conditions, therotating tool can even leave the clamping chuck of the tool holderduring operation in a marginal situation, and thus create a great hazardfor the machine operator.

SUMMARY OF THE INVENTION

It is thus the object of the present invention to provide a tool holderwith a clamping chuck, in particular a shrink fit chuck or similar, inwhich an axial migration of the rotating tool, like a spiral drill,profile drill, screw drill including tap, end facing drill, cutter,etc., is not possible during operation, but in which the rotating toolis mounted torque proof, as well as also axially fixated with respect tothe rotation axis without any migration out of the chuck.

This object is accomplished according to the invention as claimed,wherein advantageous improvements of the invention are provided by thefeatures of the dependent claims.

According to the invention, a tool holder according to the inventioncomprises a pullout preventer for the tool, which prevents axialmigration of the tool out of the tool holding fixture. Thus, the pulloutpreventer comprises at least one locking element and at least onelocking groove corresponding thereto, receiving the locking element,which interact through form locking. Thus, the locking element and thelocking groove are at least partially configured with a ball headprofile, wherein either the clamping chuck comprises the lockingelements and the tool comprises the locking grooves, or vice versa.

Furthermore, thus the locking grooves, which are disposed starting atthe face side, either on the tool shaft, or in the tool holder, can beprovided expanded with reference to the groove width, in order to thusfacilitate easier insertion of the tool into the tool holder.

In a particularly preferred embodiment, the tool holder comprises atleast two rotatably supported balls on the tool holder side, wherein onthe side of the rotation tool at least two locking grooves at the shaftof the rotation tool, which correspond to the balls, interact in a formlocking manner. The two locking grooves are thus preferably providedlike a thread at the cylindrical tool shaft starting at the face side ofthe cylinder shaft along the circumferential surface of the cylindershaft. Said locking grooves disposed on the circumferential surface ofthe cylinder shaft of the rotation tool are provided with a left pitchdirection for tools with a left groove and are provided with a rightpitch direction for rotation tools with a right groove. Thus, thelocking grooves can also be configured in axial direction and thusparallel to the rotation axis, wherein this still provides safetyagainst rotation for the tool.

In order to clamp the rotation tool according to the invention, likee.g. spiral drills, profile drills, screw drills including taps, endfacing drills, cutters, and arbors for other tools etc. in the clampingchuck according to the invention, e.g. the shrink fit chuck of the toolholder, the induction coil is initially turned on in the shrink fitchuck, this means the induction coil is connected to high frequency ACpower. Due to the Eddy currents occurring in the sleeve section of thetool holder generated by induction from the coil surrounding the toolholder, the sleeve section is quickly heated up, so that it expandsthermally, and thus the inner diameter of the receiver opening isenlarged. Now, the rotating tool can be inserted into the receiveropening with its shaft. The face of the rotating tool thus reaches theballs protruding into the inner cavity of the receiver opening and stopsthere. Depending on the pitch direction of the locking grooves of therotating tool, said tool is now rotated counterclockwise or clockwisewith respect to the rotation axis, so that the balls can engage the ballreceiving grooves. Further rotation forces a helical rotation, and thusan axial pull-in movement of the rotation tool into the shrink fit chuckor similar, until the face of the cylindrical shaft contacts the shrinkfit chuck or until the balls have reached their final position in theball receiving locking grooves. The induction coil can be turned offnow. Due to the quick cooling which occurs now, the shrink fit chuckshrinks back again to its original size, which connects the cylindricalshaft torque proof with its circumferential surface to the innercircumferential surface of the receiver opening of the shrink fit chuckwith a press fit. Since the rotation direction of the locking groovescorresponds to the rotation direction of the rotating tools during theoperation of the tool also under high load, that means, under highcutting resistance of the work piece and under large feeds of the toolor of the tool table, an axial migration of the rotation tool along therotation axis out of the chuck cannot occur anymore. Through theinteraction of the balls in the tool holder with the ball profilelocking grooves in the tool shaft, and the thread configuration of saidlocking grooves, an axial locking is accomplished. Said axial lockingcan only be released by rotating the rotating tool against the operatingdirection of the rotating tool and pulling it out of the clamping chuck.A rotation performed against the operating direction of the rotationtool during operation is thus, however, not possible when machining thework piece with the rotating tool. Furthermore, said rotating movement,due to the torque proof press fit, is not possible during operationeither. Thus, the rotating tool cannot move out of the shrink fit chuckor similar.

Thus, the machining remains precise, and the dimensions can be keptwithin the required tolerances. Since axial migration out of the chuckis prevented by the present invention, production can be run efficientlyand more economically, since, compared to prior art tool holders withclamping chucks, very little scrap is produced. Additionally, thusanother cause for accidents and thus accident risk for the machineoperator is excluded.

Instead of the rotatable balls held in a press support in the clampingchuck, also cylindrical pins with a partial or half sphere can be usedat one of the faces. These are disposed in the support bore hole insteadof the balls, wherein these pins either require a protruding shoulder,so that the cylindrical pin does not fall into the inner cavity of thereceiver opening, or an outer thread which corresponds to the innerthread of the support bore hole. Using balls has the advantage comparedto using cylindrical pins with a partially spherical or semi-sphericalhead that inserting the rotation tool is easier compared to cylindricalpins, since the balls are rotatably supported and cannot cant relativeto the cylindrical shaft. Balls can also be held in the respectivesupport bore hole using a threaded pin. Thus, the threaded pin comprisesa configuration receiving the ball even at its face, e.g. shaped as apolygonal recess or as a ball shaped depression or similar. Instead ofthe threaded pin, also mating pins, bolts or similar can be used.

The pullout preventer according to the invention for tools, inparticular for rotation tools in tool holders, with a tool holdingfixture is suited in particular for clamping chucks, like e.g. draw-incollet chucks, high precision chucks, hydraulic expanding chucks, andshrink fit chucks.

Advantageously, depending on requirements, the locking grooves in thecircumferential surfaces of the shaft of the tool are configureddifferently. Thus, the locking grooves can comprise a different lockinggroove path beginning on the face side. It can be helical, L-shaped,curved, or formed from composite paths on an enveloping surface of acylinder, which is straight in portions and/or curved. In particular, ina helical locking groove path, the direction of rotation has tocorrespond to the direction of rotation of the grooved tool. This means,for a left grooved tool, the helical locking groove has to have a leftpitch direction; for a right grooved tool, on the other hand, thelocking groove has to have a right pitch direction. Therefore, there isa locking effect of the pullout preventer.

In another embodiment, the shaft of the tool comprises an outer threadat the end, and the tool holding fixture of the tool holder comprises aninner thread corresponding thereto. In this case, the pullout preventingfeature is implemented using the outer thread at the tool, which has aleft pitch direction for a left grooved tool, and a right pitchdirection for a right grooved tool. In this embodiment, locking elementsand locking grooves become obsolete.

In a particularly preferred embodiment, the support bore holes, whichreceive the locking elements, are configured preferably from the outercircumferential surface of the tool holder until into the inner cavityof the tool holder receiving the tool. Thus, said support bore holes canbe configured perpendicular to the rotation axis of the tool holder andso that they intersect the rotation axis, and/or tangentially adjacentto the inner circumferential surface of the cavity which receives thetool. Preferably, the longitudinal axes of the support bore holes areconfigured at the same angle, and in particular in a plane perpendicularto the rotation axis of the tool.

In another particularly preferred embodiment, in particular for toolholders with shrink fit chuck, balls are supported as locking elementsin a ball retainer. Thus, the support bore holes for the respectiveballs in the ball retainer comprise a smaller. bore hole diameter withrespect to the inner circumferential surface than the diameter of thesupport bore hole. Thus, the balls cannot fall to the inside into theinterior of the tool holder, but they only reach over the inner portionof the ball retainer. The ball retainer can thus either be inserted as aseparate component in an interlocking manner into the inner cavity ofthe tool holder, or it can be machined into a sleeve. Thus, the sleevecomprises the respective support bore holes with the smaller supportbore hole diameters located towards the inner cavity. The sleeve canthus be pressed or shrunk into the inner cavity of the tool holdingfixture, welded to the tool holder, held in a form locking manner byadditional threaded pins, and/or fixated with locking elements andlocking grooves at the sleeve, as they are described according to theinvention at the shaft of rotation tools.

In a particularly preferred embodiment, in particular for shrink fitchucks, the pullout preventer comprises an additional device, whichfacilitates a support of the tool by the pullout preventer withoutclearance. Thus, the tool is pressed into the tool holding fixture outof the tool holder by a force imparting element, which is disposed e.g.concentric to the rotation axis of the tool at the bottom of the borehole of the tool holding fixture. Thus, the pullout preventer contactsthe tool without clearance. Since even a small clearance between thepullout preventer and the tool allows the tool a certain mobility, whichcan also lead to damages of the tool edges. In particular, compressionsprings in the form of coil springs, conical springs, disk springs, anddisk spring packets, and/or elastic or rubber elastic elements can beused as force imparting elements.

In another particularly preferred embodiment of a tool holder with aminimum volume lubrication, said tool holder comprises at least onetransfer piece for the minimum volume lubrication, which comprises atleast one, preferably plural channels for the pressure buildup or forthe pressure compensation. For such a tool holder with such a transferpiece, additional protection may be applied for separately from thepullout preventer. The transfer piece preferably provided as a tube,which can be also comprised of plural components, is preferably formedwith a radial flange, and preferably movably received and guided in abore hole disposed in the tool holder. The tube, which can also comprisedifferent cross section profiles, is preferably supported in the toolholder preloaded by a coil spring, wherein the cylindrical shaft of thetube preferably reaches through the coil spring. Certainly, also otherforce applying elements, like tension spring, conical spring, diskspring, and/or elastic elements and their combinations are possible. Thecoil spring is preferably disposed between the radial flange of the tubeand e.g. a bottom stop in the tool holder, whereby the tube is supportedpreloaded relative to the tool holder. The transfer piece is preferablysupported in the bore hole, so it is sealed. Thus, the tool holdercomprises at least e.g. one shaft seal and/or additional seal elements,like seal rings, seal lips, etc., concentric to the bore hole for thetransfer piece or for the tube, wherein said seal elements can also bedisposed in the tool holder and/or at the transfer piece or at the tubeitself. The channels provided in the form of passthrough bore holes, inparticular with circular cross section profile, wherein also other crosssection profiles are possible, are preferably disposed in the radialflange of the transfer piece, so that the transfer bore holes in thetransfer piece are connected to the transfer bore hole in the radialflange of the transfer piece. Along the cylindrical circumferentialsurface of the radial flange of the transfer piece, a radial recess isdisposed. Therein, an annular membrane is embedded preferably in a formlocking manner, which corresponds to the radial cutouts and which ispreferably shaped as a section of an enveloping surface of a cylinder.Thus, the circumferential surface recess, in particular provided as agroove, and also the cross section of the membrane embedded in thegroove preferably corresponding thereto, can e.g. comprise or a partialball head profile or other profiles. The annular membrane is preferablyformed from an elastic material, in particular from a rubber elasticmaterial, but also other materials are possible, like e.g. carbon fibermaterial, plastics, Teflon and flexible metals. The channels for thepressure compensation or for pressure venting or pressure buildup arethus in particular connected to the membrane and to the inner cavity ofthe transfer piece. When pressure is built up in the tool holder, themembrane thus cambers in radial direction, and thus attaches to thecircumferential surface of the receiver bore hole of the tool holder.Thus, the transfer piece is locked against axial movement.

The invention relates to a tool holder according to the preamble ofclaim 22. The invention furthermore relates to a clamping systemincluding the tool holder and a method for producing a tool receiver forthe tool holder.

From WO 2007/118626 A1 a tool holder is already known that includes anexpansion bushing arranged within a base element wherein the expansionbushing is configured to receive a tool and can be loaded with apressure fluid for clamping the tool from an outside. The tool holderfurthermore includes an extraction preventer including plural lockingelements arranged in the base element for engaging correspondingopposite elements at the tool in order to prevent axial extraction ofthe tool during machining. The locking elements in the known tool holderare configured as locking pins or balls which are moveably supported inrespective bore holes of the base element and which engage associatedlocking grooves at the shaft of a tool to be clamped. In this toolholder, however, the base element has to be machined in a complex mannerin order to be able to receive the locking elements.

Thus it is an object of the invention to provide a tool holder asrecited supra and a clamping system with a tool holder of this typewhich can be manufactured more easily and which can be mounted in asimple manner.

This object is achieved through a tool holder with the features asclaimed and through a clamping system with the features as claimed and amethod for producing a tool receiver for a tool holder of this type withfeatures as claimed. Advantageous embodiments of the invention aredefined in the dependent claims.

In the tool holder according to the invention the at least one lockingelement is integrally configured in one piece with the receiver. Thus,the receiver can be mounted in a simple manner together with the lockingelements. Furthermore no space for the receiver is lost through thelocking element. The entire available space can be used for thereceiver, so that no clamping force is lost.

The clamping system according to the invention includes a tool holderand a tool, wherein the tool holder includes a base element, adeformable receiver for clamping a tool, and at least one lockingelement integrally configured with the receiver, wherein the lockingelement engages a corresponding opposite element at the tool forpreventing an axial extraction of the tool from the tool holder.

In a particularly advantageous embodiment the receiver is an expansionbushing arranged in a receiving opening of the base element wherein theexpansion bushing can be loaded with the pressure fluid from the outsideand the at least one locking element is arranged at the inside of theexpansion bushing.

The receiver, however, can also be a shrink fit chuck that is integrallyconfigured together with the base element, a reduction bushing that isarranged within a shrink fit chuck or a collet that is arranged within areceiving opening of the base element and deformable through a clampingelement, wherein at the at least one locking element is arranged at aninside of the collet.

In an embodiment that is advantageous from a fabrication point of viewand from an assembly point of view the at least one locking element canbe formed directly at the receiver. In case of an expansion bushing thelocking element, however, can also be a separate component that isconfigured for example as a ball, a locking pin or similar, wherein thecomponent is attached at the expansion bushing.

For directly forming the locking element at the receiver the receiver isadvantageously produced according to the invention through a materialremoving method from a metal solid material by generating a recess,wherein during production of the recess for forming the locking elementintegrally configured in one piece with the receiver at least oneprotrusion is left out that protrudes in the recess. Thus, the lockingelement is integrally formed at the recess. For producing the receiverfrom a metal solid material, material removing spark erosion methodshave proven to be particularly advantageous, which methods are knownunder the abbreviation EDM (electrical discharge machining) and/orelectrochemical removal methods like ECM (electrical chemical machining)or a combination thereof like the method known as ECDM (“electricalchemical discharge machining”). With material removing methods of thistype the complex structures for forming protrusions that extend inwardin the receiver can be produced, wherein the protrusions form thelocking elements according to the invention. Thus, in order to producethe recess in a full material block initially in a first process stepchip removing methods can be used and in a final process step materialremoving electrical discharge machining methods (abbreviated EDM) and/orelectrochemical material removing methods can be used through which thefine structures for forming the protrusions are then formed in therecess, wherein the fine structures form the locking elements.

In a particularly advantageous embodiment the at least one lockingelement is configured at the receiver as an inward extending protrusionfor engaging a respective recess at the shaft of a tool to be clamped,wherein this protrusion is advantageously integrally formed with thereceiver and generated as recited supra through a material removingelectrical discharge machining method and/or through an electrochemicalmaterial removal method in a recess from a solid material block.Accordingly, the locking element provided at the receiver can also beconfigured as a recess and the associated opposite element at the toolcan be configured as protrusion. The locking element can have asemicircular or circular cross section for simplified engagement of theassociated opposite element.

In an advantageous manner the at least one locking element can extend atleast over a partial circumference of the receiver at its inside like athread turn of a nut. A support that is more even over the circumferencecan be achieved in that plural locking elements are arranged at theinside of the receiver, which locking elements extends like a threadturn of a nut at least over a partial circumference of the receiver.When there are plural locking elements they are advantageously arrangedat the receiver with even angular spacing in circumferential direction.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a sectional view of the tool holder according to theinvention, comprising a shrink fit chuck with a separate end millcutter, which is provided with locking grooves and which is not yetclamped;

FIG. 2 shows a sectional view of the tool holder according to theinvention, comprising a shrink fit chuck with an end mill cutteraccording to the invention clamped therein;

FIG. 3 shows a sectional view of the tool holder according to theinvention, comprising a shrink fit chuck with an end mill cutteraccording to the invention clamped therein;

FIG. 4 shows a sectional view of the tool holder according to theinvention, comprising a high precision chuck and an end mill cutteraccording to the invention clamped therein;

FIG. 5 shows a sectional view of the tool holder according to theinvention, comprising a hydraulic expanding chuck with end mill cutteraccording to the invention clamped therein;

FIG. 6 shows a sectional view of the tool holder according to theinvention, comprising an end mill cutter according to the inventionclamped therein, where the tool comprises an exterior thread, which isthreaded into a corresponding interior thread of the tool holder;

FIG. 7 shows a sectional view of the tool holder according to theinvention, comprising balls as locking elements, which are secured bythreaded pins;

FIG. 8 shows a sectional view of the tool holder according to theinvention, comprising balls as locking elements, which are secured bythreaded pins, where the balls are partially recessed into the threadedpins;

FIG. 9 shows a sectional view of the tool holder according to theinven-tion, comprising balls as locking elements which are secured bycylindrical pins in the press fit;

FIG. 10 shows a sectional view of the tool holder according to theinven-tion, comprising a one-piece locking element, which is a threadedpin with a ball shaped embossing at one of its faces;

FIG. 11 shows a sectional view of the tool holder according to theinven-tion, comprising one-piece locking elements, which are cylindricalpins with a ball shaped embossing at one of the faces in a press fit;

FIG. 12 shows a sectional view of the tool holder according to theinvention with balls in a separate ball retainer and a sleeve adjacentthereto;

FIG. 13 shows a sectional view of the tool holder according to theinvention, comprising balls, which are disposed in a ball retainer,which is machined into the sleeve, wherein the sleeve is pressed in orshrunk in;

FIG. 14 shows a sectional view of the tool holder according to theinvention from FIG. 13, wherein the sleeve is welded to the tool holder;

FIG. 15 shows a sectional view of the tool holder according to FIG. 13,where the sleeve is mechanically fixated by threaded pins with a conicaldome;

FIG. 16 shows a sectional view of the tool holder according to theinvention, comprising a slotted sleeve, which receives the balls, andwhere the sleeve is provided with locking grooves and held at the toolholder by additional balls and threaded pins;

FIG. 17 shows a sectional view of the tool holder according to theinvention, comprising a conical spring for a pullout preventer withoutclearance;

FIG. 18 shows a sectional view of the tool holder according to theinvention, comprising a length adjustment screw, which is formed fromrubber elastic material;

FIG. 19 shows a sectional view of the tool holder according to theinven-tion, comprising a length adjustment screw, which comprises anelement made of rubber elastic material;

FIG. 20 shows a sectional view of the tool holder according to theinven-tion, comprising a minimum volume lubrication, balls as lockingelements, and a membrane made of rubber elastic material;

FIG. 21 shows a sectional view and a side view of the tool holderaccording to FIG. 20 according to the invention with a tangentialdisposition of the locking elements;

FIG. 22 shows an enlarged illustration of a portion of FIG. 20 of thetool holder according to the invention with the membrane and a pressurechannel in the transfer piece.

FIG. 23 illustrates a tool holder with an expansion bushing forhydraulically clamping a tool in a longitudinal sectional view;

FIG. 24 illustrates the expansion bushing of FIG. 23 in a blown upsectional view;

FIG. 25 illustrates the expansion bushing in a perspective view;

FIG. 26 illustrates a view of the expansion bushing from behind;

FIG. 27 illustrates a detail view of the expansion bushing in a partialsectional view;

FIG. 28 illustrates the detail view A of FIG. 24;

FIG. 29 illustrates a first embodiment of a clamping system with toolholder, expansion bushing and tool in a sectional view;

FIG. 30 illustrates a second embodiment of a clamping system with toolholder and tool in a sectional view;

FIG. 31 illustrates a third embodiment of a clamping system with toolholder, reduction sleeve in a sectional view; and

FIG. 32 illustrates a fourth embodiment of a clamping system with toolholder, collet and tool in a perspective sectional view.

FIG. 33 illustrates a further embodiment in form of a roller clampingchuck.

DESCRIPTION OF THE INVENTION

FIG. 1 shows the tool holder 1 schematically in a sectional view and anexemplary end mill cutter 2, which are disposed relative to one anotherwith respect to a rotation axis 3. The tool holder 1 thus comprises atleast two, preferably three or four, balls 4. The ball is thus disposedin a support bore hole 5, which is disposed perpendicular to therotation axis 3, and thus to the longitudinal axis in the sleeve section6 of the tool holder 1. Said support bore hole 5 is a pass-through borehole and extends from the outside of the sleeve section 6 to the innercircumferential surface of the receiver opening 7, which is disposedconcentric with the rotation axis 3 in the tool holder 1. The frontsupport side 8 of the support bore hole 5 is provided in the shape of aspherical cap or configured according to the ball shape of the ball 4,so that the ball 4 partially protrudes into the inner cavity of thereceiver opening 7. The ball 4 is held by a threaded pin 9 in itsforward position, thus in a position protruding into the inner cavity ofthe receiver opening 7. Thus, the support bore hole 5 comprises an innerthread corresponding to the outer thread of the threaded pin 9. Thus,the length of the threaded pin 9 does not protrude beyond the outersurface of the sleeve section 6. The threaded pin 9 thus comprises ahexagonal hole 10 for an Allen wrench. The end mill cutter 2 comprisesthe helical locking grooves 13, 14 on its cylinder shaft 11 proximal tothe face 12. They comprise a ball shaped profile, which corresponds tothe ball shape of the ball 4. In order to completely clamp the end millcutter in the tool holder, the tool holder has to be rotated accordingto the rotation direction 15 during insertion of the end mill cutter, sothat the end mill cutter 2 is rotated into the receiver opening 7 in ahelical motion until the end mill cutter 2 has reached a stop.

FIG. 2 schematically illustrates a tool holder 1 in a sectional view, inwhich the end mill cutter 2 is completely clamped in. The end millcutter 2 is disposed up to its stop with its cylindrical shaft 11 in thereceiver opening 7. Thus, the ball 4, which is supported by the threadedpin 9, engages the locking groove 13 or 14. In this graphic sectionalview, the cylinder shaft 11 is press fitted in the receiver opening 7,this means, the induction coil (not shown in the drawing) is turned offand the shrink fit chuck of the tool holder 1 is cooled down and shrunkback to its original size. As clearly visible in FIG. 2, an axialmovement of the end mill 2 along the rotation axis 3 cannot beperformed, since the ball 4 is located in the ball shaped locking groove13 or 14 in the cylinder shaft 11, so that a movement along the rotationaxis 3 is blocked. Thus, the interaction between the ball 4 and thelocking groove 13 or 14 is depicted in the form of a lock. In order toremove the end mill 2 cutter from the tool holder 1, the end mill 2after switching on the induction coil only has to be rotated against therotation direction 15 (re. FIG. 1), and pulled in axial direction alongthe rotation axis 3 out of the tool holder 1.

In the subsequent figures, viable embodiments are illustrated, showinghow the pullout preventer is configured in other state of the artclamping tools.

FIG. 3 shows a typical draw-in collet chuck with cap nut with thepullout preventer with the locking grooves and balls in a schematicsectional view.

FIG. 4 shows a high precision chuck with the pullout preventer accordingto the invention through locking grooves and balls.

FIG. 5 shows a typical hydraulic expansion chuck with the pulloutpreventer according to the invention through locking grooves and ballsin a schematic sectional view.

FIG. 6 shows a tool holder provided as shrink fit chuck in a schematicsectional view, where the end mill cutter is bolted to the tool througha thread 16. Through this threaded connection, which is configured witha left pitch direction for a left grooved tool, and a right pitchdirection for a right grooved tool, an axial pullout prevention of thetool from the tool holder is implemented.

FIG. 7 shows a shrink fit chuck in a schematic sectional view withlocking elements in the form of balls 4, which are held in therespective support bore holes 5 with threaded pins 9. The threaded pin 9thus comprises a blunt face.

FIG. 8 shows a shrink fit chuck with locking elements configured asballs 4 in a purely schematic sectional view, where the balls are heldin the support bore holes 5 by threaded pins 9. The threaded pin 9comprises a recess 17 on the face receiving the ball 4. The recess 17 isconfigured as a dead hole or e.g. configured as bushing with an interiorhexagonal shape corresponding to the diameter of the ball.

FIG. 9 shows a shrink fit chuck with locking elements provided as balls4 in a purely schematic sectional view, where the balls are held in thesupport bore holes 5 by alignment pins 18. Due to the press fit betweenthe alignment pin 18 and the support bore hole 5, the locking elementsprovided as balls 4 are fixated in their position.

FIG. 10 shows a shrink fit chuck with one-piece locking elements 19 in apurely schematic sectional view. The locking element 19 is a threadedpin, which comprises a semi-spherical head 20 at one of its faces.

FIG. 11 shows a shrink fit chuck with a one-piece locking element 19 inthe support bore holes 5 in a purely schematic view. The one-piecelocking elements 19 are alignment pins, which are connected to theshrink fit chuck through a press fit. The one-piece locking elements 19comprise a semi-spherical head 20 on one of their faces.

FIG. 12 shows a shrink fit chuck with locking elements in the form ofballs 4 in a purely schematic sectional view. The balls 4 are supportedin a ball retainer 21. Thus, the ball retainer 21 is disposed at thebottom of the receiver opening 7. Adjacent thereto, there is a sleeve22. In the retainer 21, the balls 4 are recessed, which are pressed bythe retainer to the radial outside. Thus the balls 4 are thus pressedagainst a shoulder, which is disposed between the receiver opening 7 anda rotation relief at the end of the receiver opening 7. The balls 4 canbe radially supported at said shoulder. When the tool is shrunk in, theballs 4 are supported towards the inside and can secure the tool 2 aswell as the sleeve 22 against an axial pullout.

FIG. 13 shows a shrink fit chuck with balls 4 in a purely schematicsectional view, where the balls are disposed in a sleeve 22 in the leftsection of the sleeve and in the receiver opening 7. The left section ofthe sleeve 22 thus functions as a ball retainer for the balls 4. Thesupport bore holes 5 for the balls 4 in the sleeve 22 comprise a smallerdiameter with reference to the inner cylindrical circumferential surfaceof the sleeve 22, than the diameter of the balls or the diameter of thesupport bore hole. Thus, the balls 4 can protrude into the inner cavitybut they cannot fall in. The sleeve 22 is either shrunk or pressed intothe chuck.

FIG. 14 shows a shrink fit chuck with balls 4 in a sleeve 22 in a purelyschematic sectional view. The sleeve 22 is connected to the sleevesection 6 by a weld 23. The weld of the sleeve 22 with the shrink fitchuck can thus be performed in spots in sections or annular as a closed-or Y-weld.

FIG. 15 shows a shrink fit chuck with balls 4 in a sleeve 22 in a purelyschematic sectional view. In this embodiment, the sleeve 22 is fixatedto the tool holder by threaded pins 24. Thus, the threaded pins 24 e.g.comprise a conical cap. Certainly also other embodiments, like e.g. aball head, are possible. The sleeve 22 comprises indentations 25corresponding to the face configuration of the threaded bolts 24, wheresaid indentations are configured corresponding to the face capconfiguration of the threaded pins 24. In the present embodiment, saidindentations 25 are configured conical. In order to fixate the sleeve 22at the tool holder, at least one threaded pin 24 with a conical faceconfiguration or with an overall conical configuration is necessary.Preferably, three, in particular four threaded bolts for fixating thesleeve 22 are disposed at the tool holder.

FIG. 16 shows a shrink fit chuck with the locking elements provided asballs 4, disposed in the sleeve 22, in a purely schematic sectionalview. The sleeve 22 is thus configured thicker than in the precedingfigures. Therefore, the sleeve 22 is slotted (not shown in the drawing).In this embodiment, the sleeve 22 is also connected to the tool holderby balls. Thus, locking grooves 27 corresponding to the balls aredisposed in the left portion of the sleeve 22, where said grooves have aprofile corresponding to the balls. The same way as the tool is axiallyfixated in the shrink fit chuck through the interaction of lockingelements and locking grooves, the sleeve 22 is axially fixated throughballs 26 as locking elements with locking grooves 27 in the outercircumferential surface of the sleeve 22. The balls 26 are thus disposedin support bore holes 28, which in turn connect threaded pins 29 amongstone another by a thread. Also in this case, the support bore hole 28comprises a smaller diameter in the inner portion in the directiontowards the receiver opening 7, than the diameter of the support, whichcorresponds to the ball diameter of the ball 26. Thus, the balls 26cannot fall into the interior cavity, but they protrude into it.

FIG. 17 shows a shrink fit chuck with an axial pullout preventeraccording to FIG. 2 in a purely schematic sectional view. Additionally,the tool holder comprises a conical spring 30, which is disposed betweenthe face side 12 of the cylinder shaft 11 of the end mill cutter 2 andthe bottom 31 of the receiver opening 7. The compression spring providedas a conical spring 30 thus presses onto the face 12 of the end mill 2cutter in the direction of the rotation axis 3 out of the tool holder 1.Thus, a possible clearance or manufacturing tolerances of the lockinggrooves in the circumferential surface of the cylinder shaft 11 and therespective position of the balls 4 in the tool holder 1 are eliminated,in as far as the end mill cutter 2 is additionally locked in axialdirection by the force of the conical spring 3. Thus, also a smallclearance between the axial pullout preventer and the tool can beeliminated. Thus, there is no risk to additionally damage the cuttingedges of the tool during operation, due to small manufacturingtolerances.

FIG. 18 shows a shrink fit chuck with the locking elements in the formof balls 4 in a purely schematic sectional view. Herein, a pulloutprevention of the tool without clearance is performed after shrinking inthrough the use of a length adjustment screw 32, which is preferablymade of a rubber elastic material. Corresponding to the lengthadjustment screw 32, a corresponding inner thread 33 is formed in thetool holder. In FIG. 18, another embodiment for the path of the lockinggroove is shown. In this embodiment, the locking groove 34 is providedin the shape of an “L”, but starting at the face 12 of the cylindershaft 11. Thus, a quasi bayonet lock for an axial safety is provided asa pullout safety for the tool from the tool holder.

FIG. 19 shows a shrink fit chuck from FIG. 18 in a purely schematicsectional view, wherein an elastic element 35 is integrated therein,concentric to the length adjustment screw 32. In this case, the elasticelement 35 is preferably made of a rubber elastic material. The pulloutprevention without clearance is performed through the compression force,which is imparted through the length adjustment screw 32 to the elasticelement 35 through the face 12 to the end mill cutter 2.

FIG. 20 shows a shrink fit chuck with a minimum volume lubrication (MMS)in a purely schematic sectional view. The axial pullout prevention isperformed by locking elements 36, which are in turn provided as balls.Concentric to the rotation axis in the interior of the shrink fit chuck,there is a movable tube 37, which is the transfer piece for the minimumvolume lubrication. The tube 37 is pressed against the tool shaft (notshown in the drawing) due to the spring force of a coil spring 38. InFIG. 20, two possible end positions of the tube 37 are shown. Thecontact surface of the tube disposed on the right with the tool shaft isprovided conical in the shape of a radial tubular flange 39. The coilspring 38 is thus concentrically permeated by the tube 37. The coilspring 38 is disposed between the bottom 31 and the cone section shapedcircumferential surface of the tube 37 at the radial neck flange. FIG.21 illustrates the tangential disposition of the locking elements 36 inthe tool holder along the section line A-A of FIG. 20 in a purelyschematic sectional view. FIG. 22 shows an enlarged detail of FIG. 20,which is marked by a dashed line. In a radial neck flange 39 of the tube37, pass-through bore holes 40 are disposed, which ex-tend from theinner diameter of the tube 37 to the outer circumferential surface 41 ofthe radial tubular flange 39. Along the cylindrical circumferentialsurface 41 of the radial tubular flange 39 of the tube 37, a concentriccylinder surface shaped recess 42 is disposed, whose width is preferablysmaller than the width of the cylindrical circumferential surface 41 ofthe tubular flange 39. Corresponding to the recess 42, an annularmembrane 43 formed as a section of an enveloping surface of a cylinderis disposed, which is formed flush with the outer cylindricalcircumferential surface 41 of the tubular flange 39. The membrane 43 isthus preferably formed from a rubber elastic material. Said membrane 43along the circumferential surface 41 seals the tube 37 against the wallof the receiver opening 7 of the shrink fit chuck. The bore holes 40,which radially lead to the inside of the membrane 43, pass the airpressure onto the membrane 43, which is thus pressed against the wall 7of the bore hole. Through the pressure buildup, the membrane cambers inradial direction and thus attaches to the inner circumferential surfaceof the receiver opening 7 of the tool holder. Thus, the tube 37 issecured as a transfer piece for the minimum volume lubrication againstaxial displacement. Through the movable tube 37, the lubricant mist canbe conducted to the tool without loss.

FIG. 23 illustrates a longitudinal sectional view of a tool holder 50illustrated as HSK tool holder including a rotation symmetrical baseelement 51 and an expansion bushing 52 arranged in the base element 51for receiving the cylindrical shaft of a tool that is not illustrated.The base element 51 includes a cylindrical front portion 53 with areceiver opening 54 for the expansion bushing 52 and a conical rearportion for reception in an operating spindle of a machine tool. Betweenthe cylindrical front portion 53 and the conical rear portion 55 anengagement groove 56 is provided at the outside of the base element 51.

The expansion bushing 52 that is separately illustrated in FIG. 24includes two circumferential recesses 57 at its outside that are offsetfrom one another and an annular shoulder 58 at its front end. Betweenthe recesses 57 and the inner wall of the base element 51 in the portionof the receiver openings 54 pressure cavities 59 that are illustrated inFIG. 23 are defined for receiving a pressure fluid. The expansionbushing 52 is advantageously firmly connected at its forward and rearend with the base element 51. It can be soldered to the base element 51or it can be permanently connected with the base element 51 in anothermanner. The pressure cavities 59 are connected with a pressure cavityarranged in the base element 51 through channels in the base element 51that are not illustrated herein, wherein the volume of the pressurecavity is variable for example through a piston that is adjustablethrough a bolt. Through adjusting the piston through the bolt, apressure of the pressure fluid arranged in the pressure cavity and inthe pressure chamber 59 can be increased and thus the expansion bushing52 can be pressed radially inward. Through the known arrangement whichis therefore not illustrated the expansion bushing 52 can be evenlypressed against the cylindrical shaft of a tool to be clamped that hasbeen inserted into the expansion bushing 52 which facilitates a centricand full surface clamping with high clamping force.

At the inside of the expansion bushing 52 inward protruding lockingelements 61 are provided in a rear portion 60 that has an expanded innerdiameter, wherein the locking elements extend like a thread turn of anut and engage corresponding opposite elements 62 at a cylindrical toolshaft 63 of a tool 64 that is illustrated in FIG. 29. The oppositeelements 62 are configured like a thread turn of a bolt. Through thelocking elements 61 engaging respective opposite elements 62 at the tool64 an extraction safety is provided which prevents an axial extractionof the tool 64 that is caused for example by vibrations duringprocessing.

In the illustrated embodiment the locking elements 61 are configured asprotrusions with semi circular cross sections extending incircumferential direction in helical shape. As apparent from FIG. 26three protrusions are provided in the embodiment that are spaced witheven angular offsets in circumferential direction which are provided aslocking elements 61 in the form of thread turns of a nut, wherein thelocking elements extend at an inner wall of the expansion bushing 52like a three turn inner nut thread respectively with identical pitch.The opposite elements matching the locking elements 61 are configured aslocking grooves which are configured like a three path bolt thread at anoutside of the cylindrical tool shaft 63 of a tool 64 starting at therear face and extending in a helical shape along the circumferentialsurface.

The expansion bushing 52 is advantageously produced according to themethod according to the invention from a metal solid material block,(for example a solid cylinder) by producing a recess through a materialremoving electrical discharge machining method like e.g. EDM or EDCM,wherein the locking elements 61 are left out in the cylindrical recessas inward extending protrusions when generating the recess.

For inserting a tool into the tool holder 50 the tool when inserted intothe tool holder 50 initially has to be rotated so that the lockingelements 61 come into engagement at the expansion bushing 52 with therespective opposite elements 62 at the tool 64. Then the expansionbushing 52 can be loaded with pressure fluid from the outside. Thepressure presses the expansion bushing 52 in inward direction whichclamps the tool 64. Through the form locking engagement of the lockingelements 61 in the associated opposite elements 62 an axial extractionof the tool 64 from the tool holder 50 can be prevented.

FIG. 29 illustrates a clamping system with a tool holder 50, anexpansion bushing 52 and a tool 64 configured for example as a mill or adrill. Differently from the embodiments in FIGS. 23-28 the expansionbushing 52 only includes a recess 57 at its outside for forming apressure cavity 59. Also in this embodiment inward protruding lockingelements 61 are provided at the inside of the expansion bushing 52,wherein the locking elements are provided as helically extendingprotrusions for engaging opposite elements 62 configured as lockinggrooves at the cylindrical tool shaft 63 of a tool 64.

FIG. 30 illustrates another embodiment of the clamping system with toolholder 50 and a tool 64 configured as a mill, drill or similar. In theembodiment the receiver is configured as a shrink fit chuck 65 that isintegrally configured with the base element 51. In a tool holder 50 ofthis type the shrink fit chuck 65 is thermally heated for examplethrough induction which increases the interior diameter of the shrinkfit chucks 65. In heated condition a tool 64 is inserted into the shrinkfit chuck 65, wherein the ratio of the inner diameter of the shrink fitchuck 65 to the outer diameter of the cylindrical tool shaft 63 isconfigured so that the tool 64 is firmly supported in the shrink fitchuck 65 during subsequent cooling of the shrink fit chuck 65. In thisembodiment inward protruding locking elements 61 are configured at aninside of the shrink fit chuck 65, wherein the locking elements areconfigured as helical protrusions for engaging the opposite elements 62configured as locking grooves at the cylindrical tool shaft 63 of a tool64.

In an additional embodiment illustrated in FIG. 31 the receiver is alsoconfigured as a shrink fit chuck 65 that is integrally configured withthe base element 51. Herein, however, the tool 64 is clamped within theshrink fit chuck 65 through a reduction sleeve 66. The reduction sleeve66 is configured in a known manner as a slotted sleeve with plural axialslots and an inner diameter adapted to the outer diameter of thecylindrical tool shaft 63. The reduction sleeve 66 also includes inwardprotruding locking elements 61 at its inside, wherein the lockingelements are configured as helical protrusions for engaging oppositeelements 62 at the cylindrical tool shaft 63 of a tool 64 configured aslocking grooves. The reduction sleeve 66 furthermore includes helicallocking grooves 67 at its outside for engaging locking elements 68 whichare formed as inward protruding helical protrusions at the inside of theshrink fit chuck 65. Thus, an extraction safety to prevent axialextraction of the reduction sleeve 66 is implemented.

FIG. 32 illustrates another embodiment in which the receiver isconfigured as a collet 71 that is arranged within a receiving opening 69of the base element 51 and deformable through a clamping element 70. Thecollet 71 includes an outer cone surface 72 for contacting an inner conesurface 73 of the

receiving opening 69. The cone surfaces 72 and 73 are adjusted to oneanother so that the collet 71 can be compressed in inward directionthrough axial movement so that it clamps a cylindrical tool shaft 63 ofa tool 64. The collet 71 also includes inward protruding lockingelements 61 at its inside, wherein the locking elements are configuredas helical protrusions for engaging opposite elements 62 at thecylindrical tool shaft 63 of a tool 64 configured as locking grooves.The axial movement of the collet 71 is also provided through theclamping element 70 which is configured herein as a threaded ring thatis threaded onto an external thread at a front end of the base element51.

In another embodiment which is illustrated in FIG. 33, the tool holderis configured as a so-called roller clamping chuck, which is acollet-like clamping chuck. Similar to the embodiment illustrated inFIG. 30, the tool holder 50 is provided with a clamping chuck 79 toreceive the tool. On a front portion of the clamping chuck 79 a clampingelement or nut 70 is arranged which is typically rotatably supportedthrough a needle bearing 80 or another roller bearing wherein the atleast partially deformable clamping element or nut 70 can impart aclamping pressure onto the clamping chuck 79 by being rotated. Theneedle bearings are supported within a bearing cage roll on the taperinginner surface 81 of the clamping element or nut 70 and on a taperingouter surface 82 of the front portion of the clamping chuck. When theclamping element or nut 70 is turned then the space between the taperinginner surface 81 of the clamping element or nut 70 and the taperingouter surface 82 of the front portion of the chuck 79 is reduced and theclamping nut presses against the front portion of the clamping chuckthrough the needle rollers in order to press the clamping chuck againstthe tool shaft for tightening the tool. The inner circumferential faceof the clamping chuck 79 of the tool holder 50 is provided withlongitudinal grooves 84 which are parallel to the longitudinal axis ofthe tool holder 50 which serve to make the clamping chuck portiondeformable so that the tool shaft can be clamped when the clampingelement or nut 70 is tightened.

In addition the locking elements 85 formed in the inner circumferentialface 83 can be seen from FIG. 33 which are co-acting with the lockinggrooves 86 at the shaft 87 of the tool 88. Of course the number oflocking elements 85 corresponds with the number of locking grooves 86and the circumferential distance between the locking elements is thesame as the distance between the locking grooves.

The invention is certainly not limited to HSK tool holders also SK-,WS-, BT-, ABS-, or Capto-interfaces and similar can be accordinglyprovided at the base element 2.

1. A combination of a tool holder and a rotation tool, the combinationcomprising: a rotation tool having a shaft with an end face and acircumferential surface; a tool holder having a clamping chuck being adeformable receiver for receiving and clamping the rotation tool in acentral axial opening thereof; a pullout preventer configured to locksaid rotation tool in said tool holder against an axial migration out ofsaid central axial opening of said tool holder; said pullout preventerincluding at least one locking element, being a part of said toolholder, and at least one locking groove formed in said rotation tool,with said at least one locking groove and said at least one lockingelement being complementarily formed and disposed to engage one anotherand to lock said rotation tool against the axial migration out of saidtool holder.
 2. The combination according to claim 1, wherein saidlocking element is configured to project inward into said central axialopening in said tool holder and into said locking groove in said shaftof said rotation tool when said rotation tool is mounted in said toolholder.
 3. The combination according to claim 2, wherein said at leastone locking groove begins at said end face and extends in saidcircumferential surface from said end face in a straight linear path, ina curved path, in an L-shaped path, or in a composite path with aplurality of segments.
 4. The combination according to claim 2, whereinsaid locking element is a forward head of a locking element being a pinprojecting through support bore hole formed in a wall of said toolholder and into said locking groove.
 5. The combination according toclaim 1, wherein said locking element is integrally formed with saidreceiver.
 6. The combination according to claim 1, wherein said at leastone locking element and said at least one locking groove are configuredat least as a partial ball head.
 7. The combination according to claim1, wherein said at least one locking groove is one of at least twolocking grooves and said at least one locking element is one of at leasttwo locking elements.
 8. The combination according to claim 7, whereinsaid at least one locking groove is one of four circumferentiallydistributed locking grooves and said at least one locking element is oneof four locking elements.
 9. The combination according to claim 1,wherein said at least one locking groove has a helical surface pathhaving a left pitch direction for the rotation tool with a left groove,and a right pitch direction for the rotation tool with a right groove.10. The combination according to claim 1, wherein said clamping chuck isa draw-in collet chuck, a precision chuck, a hydraulic expanding chuck,or a shrink fit chuck.
 11. A rotation tool, comprising: a shaft with anend face and a circumferential surface, and a tool head opposite saidshaft; said shaft being formed for insertion into a tool holder with aclamping chuck for driving rotation of the tool about a rotation axis;said shaft of said rotation tool being formed with at least one lockinggroove that begins at said end face and extends in, and terminates in,said circumferential surface; and said locking groove being formed forengagement by a locking element of the tool holder, that locks therotation tool against an axial migration out of said tool holder. 12.The rotation tool according to claim 11, wherein said locking grooveextends along a path that is non-parallel to the rotation axis in astraight linear path, in a curved path, in an L-shaped path, or in acomposite path formed in mutually different shapes that are linearlyoffset from one another;
 13. The rotation tool according to claim 11,wherein said at least one locking groove is formed to receive and meshwith a partial ball head.
 14. The rotation tool according to claim 11,wherein said at least one locking groove is one of at least two lockinggrooves formed in said shaft diametrically opposite one another relativeto the rotation axis.
 15. The rotation tool according to claim 11,wherein said at least one locking groove has a helical surface path witha left pitch direction of the rotation tool with a left groove, and aright pitch direction for the rotation tool with a right groove.
 16. Therotation tool according to claim 11, configured for insertion in adraw-in collet chuck, a precision chuck, a hydraulic expanding chuck, ora shrink fit chuck.
 17. A tool holder for a rotation tool, the toolholder comprising: a clamping chuck formed with a central axial openingfor receiving and clamping the rotation tool therein; a locking elementdisposed to project into said central axial opening; said central axialopening forming a receiver for receiving a shaft of a rotation tooltherein, wherein the shaft is formed with a locking groove configured toengage with said locking element that projects into said central openingand said locking element is configured to mesh with the locking grooveand to lock said rotation tool against an axial migration out of saidtool holder.
 18. The tool holder according to claim 17, wherein saidclamping chuck is formed with at least one support bore hole extendingradially from an exterior thereof and into said central axial opening,and a pin configured for insertion into said support bore hole is formedwith said locking element that projects into said central axial openingand into the locking groove of the rotation tool when the rotation toolis mounted in the tool holder.
 19. The tool holder according to claim17, wherein said at least one locking element is one of at least two, atleast three, or four locking elements projecting into said central axialopening and distributed about a rotation axis of the tool holder. 20.The combination according to claim 17, wherein said locking element isintegrally formed with said receiver.